Today is the Oconee County man's last day at the U.S. Environmental Protection Agency's research lab in Athens. The EPA says it's simply a contractual thing, the result of a settlement Lewis signed in 1998 to settle one of several whistleblower complaints Lewis filed against the agency.

David Lewis sorts Tuesday through items in his office at the Environmental Protecting Agency lab in Athens. Lewis, an EPA scientist, has been a consistent critic of the agency, contending politics play a role in its policy decisions. Today is his last day on the job, pursuant to an agreement reached in a settlement of legal action he filed against the EPA.Jeff Blake/Staff

Lewis says he is being forced to retire after 32 years because his work has challenged the quality of scientific research at EPA, particularly on one issue - whether using sewage sludge as fertilizer is safe.

Sludge, a mixture of human, industrial and other waste from which water has been removed, can contain traces of household chemicals, bacteria, metals and other toxic substances. EPA allows it to be used on land after treatment to make it safer, but it can remain a health risk, according to research Lewis and others published last year.

Lewis believes the sludge issue is just one example of EPA rules being based on political expediency, not good science.

EPA officials cut off his research funding, tried to silence him and tried to force him out of the EPA, said Lewis, who has collected more than $100,000 in damages and legal fees from the agency after filing claims that administrators retaliated against him for publishing his research.

A coalition that includes Republican U.S. senators and the Sierra Club has taken his side, but apparently to no avail.

Lewis, 55, expects today to be his last at the EPA. For a long time, ''I really could not believe that the EPA could follow through with this,'' but the reality has finally sunk in, he said.

''I have given up hope (of keeping his job),'' Lewis said Tuesday. ''My attorney called me this afternoon and wanted me to try a couple more things, but I just told him I'm burned out. The clock has just run out.''

''I think it's outrageous,'' said Caroline Snyder, a member of the Sierra Club's national task force on sewage sludge and a retired environmental studies professor at Rochester Institute of Technology. ''Here's a person who's doing his job, fulfilling his obligations. They should treasure somebody like that. To cut him off is a waste of money, and a waste of a good scientist.''

Lewis' story may say more about the atmosphere for scientists in federal agencies than it says about Lewis, said David Gattie, a co-author with Lewis in a 2002 study linking sludge use with a variety of health problems.

''David is one of the few, if not the lone dissenting voice within EPA who has spoken out in support of better science,'' said Gattie, a professor of environmental and ecological engineering at the University of Georgia. ''I hate to see that voice silenced, and I feel like that's what's happened.''

For now, Lewis still has adjunct faculty status at UGA and will be allowed to keep an office in the marine sciences department. With other faculty there, he's submitting funding proposals that might get him research funding.

Lewis wouldn't change anything, he said.

Not many would have resisted the pressure his bosses put on him to stop, Snyder said.

''He's a remarkable person. Nobody else would have had the stomach,'' she said.